A subject of the invention is a method and kits for diagnosing Alzheimer""s disease.
The general increase in longevity favours the frequency with which Alzheimer""s disease occurs and this pathology constitutes a major economic problem for modern societies. A significant research effort has been carried out in order to understand the genesis of this disease, but attempts to find an early marker have been unsuccessful or incomplete. Clinical examination is most frequently used alone and certain diagnosis is only made after cerebral biopsy or autopsy.
Recently, an American team proposed the use of cholinergic antagonists in the measurement of pupil dilation as a screening test (Scinto et al., 1994, Science 266: 1051-1054). However, this test does not allow the absolute discrimination of patients suffering from Alzheimer""s disease. Its diagnostic use has been brought into question in several more recent studies.
Finally, it has also been shown recently that serum originating from patients suffering from Alzheimer""s disease contains antibodies capable of recognising antigens expressed by the microglial cells of mice. The reasons for this property and its diagnostic value have not been established for the moment.
The observation of various anomalies in patients suffering from Alzheimer""s disease has led the inventors to study the relationships between these anomalies and modifications to the activation levels of certain enzymes.
Therefore, taking into account the relationships previously established between a chloride transport anomaly in erythrocytes, in patients suffering from Alzheimer""s disease and an anomaly in the activity of protein kinase C (abbreviated to PKC), their work has at first been carried out on measurement of the activation level of PKC in the erythrocytes of such patients.
The inventors then noted that by varying the measurement conditions, it was possible to make available data which allows the discrimination of patients suffering from the disease form healthy subjects.
Development of their work allowed verification of such measurements applied to PKA, or also using a set of compounds capable of interacting with PKC or PKA, which can also be used to discriminate patients suffering from Alzheimer""s disease.
Therefore, an aim of the invention is to provide a method for diagnosing Alzheimer""s disease which allows a reliable test to be established, which is rapid and of low cost.
It also aims to provide kits which allow an easy implementation of such a method.
The method for diagnosing Alzheimer""s disease according to the invention is characterized in that it includes:
the incubation of a blood sample with one or more fluorescent probes under conditions which allow a specific bond between the probe or probes with PKC or PKA, and
measurement of the fluorescence intensity of the preparation obtained and its possible variations by the addition of inhibitor or activator of said enzyme, a variation in the emission spectra data relative to those of the spectra obtained with healthy subjects, being a discriminant vis-à-vis Alzheimer""s disease.